Dual torque yarn and method of making same



nited Sttes Patent 9 M DUAL TORQUE YARN AND METHOD OF MAKING SAME Marvin H. Comer and Devoy W. Terrell, Burlington, and Charlie A. Miles, Alamance, N .C., assignors, by mesne assignments, to Patentex, Inc., New York, N .Y a corporation of New York No Drawing. Application June 6, 1956 Serial No. 589,580

6 Claims. c1. 57-140) This invention relates to improved lively synthetic yarns and the method of making the same and is concerned, in particular, with yarn produced by the apparatus and method disclosed in our co-pending application, Serial No. 588,069 filed May 29, 1956, and entitled Apparatus and Method for Producing Dual Torque Yarns of which the present application is a continuation-in-part.

In the knitting of highly stretchable hosiery and other stretchable fabrics made from synthetic yarn, such as nylon and the like, it is customary to knit spaced portions or courses from a lively yarn which has been twisted in one direction and to knit intervening portions or courses from another lively yarn which has been twisted in the opposite direction in order that the torque influenced in the fabric by the yarns is equalized in opposite directions; i.e., balanced, and to thereby prevent the resultant product from curling or twisting so that it will lie flat. The use of two oppositely twisted yarns has many disadvantages, the most outstanding of which is the requirement for two yarn feeds in kniting operations, especially in kniting seamless hosiery, because of special attachments being required on the knitting machines in order to provide the two yarn feeds and separate stitch forming cams for each of the yarn feeds. Also, in kniting full fashioned hosiery, the use of two oppositely twisted yarns requires that two yarn carriers are alternately brought into operation in knitting complementary portions of stockings. It is also apparent that the use of two oppositely twisted yarns requires that each yarn be twisted separately from the other, that each yarn be individually threaded through the various machines employed during the twisting of the yarn and in the various knitting and weaving operations and which is time-consuming and expensive.

It is an object of this invention to provide an improved lively synthetic yarn in the form of a single continuous element which is lively throughout its length, but which has a balanced torque, or at least, a dual torque, so as to obtain stretchability in the resulting fabric without the necessity of using oppositely twisted yarns. Prior to the development of our improved method and apparatus disclosed in said copending application, no means had been devised for producing a satisfactory yarn of this character.

More specifically, it is an object of this invention to provide a novel lively synthetic yarn, such as nylon, Dacron, Arnel or any other synthetic filamentary yarn which is capable of being heat set, and a method of making the same, wherein the yarn has recurring spaced portions of predetermined length which have a latent torque in one direction with intervening portions between said recurring portions which have a latent torque in the Opposite direction and wherein immediately adjacent portions of the yarn having oppositely torsional tendencies are immediately contiguous, that is, there is no lag or torqueless portions between adjacent opposite torque portions.

Stated in another way, it is an object of this invention 2,909,028 Patented Oct. 20, 1959 to provide a lively synthetic yarn such as nylon and the like which has spaced recurring portions therein of predetermined length which are twisted in one direction with the twist being heat set therein and which has intervening portions between, and contiguous to, the recurring portions which are twisted and heat set in the opposite direction from said recurring portions with the result that the yarn is lively throughout its length and has a balanced or dual torque without lag areas between adjacent oppositely twisted portions thereof.

In producing the improved lively synthetic yarn, an end of yarn is continuously withdrawn from a pirn or yarn package past a suitable heating element, twisted in one direction and then untwisted and then wound onto a takeup bobbin. As the yarn is being withdrawn a setting heat is applied, during the twisting and in ad- Vance of the untwisting steps, to alternate sections of predetermined length of the yarn end by the heating element. This produces a yarn having alternate heat set sections having a twist torque and alternate unset nontorque sections. As the yarn is untwisted following the initial twisting, the unset portions of the yarn are untwisted to substantially zero twist and the set portions of the yarn are untwisted to impart a reverse-torque, resulting in the liveliness or torque in the latter portions.

The yarn thus far produced is then continuously withdrawn from the takeup bobbin past and in constant heat setting relation to a heating element and twisted in the opposite direction throughout its length and then untwisted. As the yarn is being twisted in the opposite direction, the setting temperature continuously applied thereto is sufficient to set the twists in the previously unset sections, but insufficient to remove the set from the previously set sections. The resultant yarn then comprises alternate sections of high torque in one direction with contiguous intervening sections of high torque in the opposite direction without any lag or torqueless portions between contiguous sections thereof. The setting temperature applied to the yarn must necessarily be suflicient to maintain liveliness of the yarn during any further processes to which the yarn or fabric made therefrom may be subsequently subjected. But the temperature initially applied intermittently to the yarn to set the twists in alternate sections thereof must be somewhat greater, for instance 25 F. to 30 F., than that subsequently applied continuously to the yarn to set the reverse twists in the previously unset sections to insure that the alternate sections initially twisted and heat set are not affected.

The yarn may be of monofilament or multifilament structure and the heat set alternate reverse twists therein may be imparted thereto on any of various types of conventional twisting machines in which the twisting spindle or head is disposed closely adjacent the heating element so that the yarn is twisted while it is being subjected to the setting temperature and untwisted between the spindle and the takeup roll so as to produce a so-called false twist in the yarn. An apparatus for producing dual torque yarn of the aforesaid character is disclosed and claimed in the co-pending application previously referred to.

In practice, it has been found that adjacent oppositely twisted portions of the yarn may be from two inches to one-hundred inches long, regardless of the denier of the yarn, although it is preferable that the recurring lengths or portions of the yarn twisted in each direction are approximately fifty inches long, since in knitting the usual stocking, whether it be full fashioned or seamless, each course requires approximately twelve and one-half inches of yarn and the fifty inch length of yarn is, thus,

equivalent to four knitted courses. In other words, in

knitting a stocking in which each oppositely twisted por-.

four courses, with four intervening courses therebetween, would be twisted in one direction and the four intervening courses, in each instance, would be twisted in the other direction. Of course, it is contemplated that the yarn may be unbalanced; i.e., portions or a portion of the yarn twisted in one direction may be thirty inches long and the adjacent portions or portion of the yarn twisted in the other direction may be sixty inches long, for example.

Present demand for lively yarns is predominantly for sheer or mono'filament yarns. However, it is to be understood that the principles of the present invention may be equally applied to multifilament thermoplastic yarns of any practical size or denier which are capable of being heat set to produce lively or stretchable characteristics. As heretofore stated, such yarns as nylon; a polyamide, Arnel; a triacetate, Dacron; a polyester, or other thermoplastic yarns may be used.

By way of example, in twisting monofilament yarn, it is preferable that each strand is subjected to a temperature of 450 F., although this temperature may vary from 300 F. to 500 F., just so long as the temperature of any subsequent treatment will not remove the set from the yarn. Synthetic yarns of seven denier to forty denier may be twisted from five to eighty turns per inch, although it is preferred that the number of turns of twist per inch imparted to the yarn be according to the denier of the yarn substantially as appears in the following table:

Denier of yarn:

As a specific example of the method by which the improved yarn is made and a further illustration thereof, apparatus of the character described in our said copending application may be used wherein yarn is drawn from a source by a withdrawing mechanism and moves past a heating element, through a twisting head and thence to :a take-up mechanism. A single end of 1S denier monofilament nylon yarn is first passed through the twisting apparatus operating at a speed and direction to impart 30 turns of S-twist per inch to the yarn between the twisting head and the withdrawing mechanism. On the other hand, the yarn is untwisted or back twisted a like amount between the twisting and the take-up mechanism.

As the yarn moves past the heating element and while the twist is being imparted thereto, alternate sections of the yarn of approximately 50 inches in length are permitted to contact the heating element or to, at least, occupy heat-setting relation with the heating element. intervening sections of the yarn of about 50 inches in length are maintained out of contact with the heating element sufiicient'ly to prevent the yarn from being heat set at such intervening sections. Thus, 30 turns per inch of S-twist are imparted to a first section of the yarn and heat-set and then this section of yarn is untwisted for 30 turns resulting in a twist torque of 30 turns in this 50 inch section. The adjacent intervening section will have 30 turns of S-twist imparted thereto and is not set and it is then untwisted a like amount, resulting in substantially no twist or torque in this section of the yarn.

The yarn is then run through the twisting apparatus again. The apparatus is run to impart 30 turns of Z- twist to the yarn between the twisting head and the Withdrawing mechanism and to untwist the yarn a like amount between the twisting head and the take-up mechanism. The yarn in this subsequent process is subjected to heat-setting throughout its entire length at an effective temperature less than that used in the first twisting. Thus, the 50 inch section of yarn which previously had been twisted 30 turns per inch 8, heat set, and untwisted 30 turns per inch Z, will have an additional 30 turns of Z-twist torque per inch imparted thereto making a total twist torque equivalent to 60 turns per inch. The yarn is set at a lower temperature than its original setting and then untwisted 30 turns per inch leaving a net twist torque of 30 turns per inch in this section of yarn. The section of yarn which previously had been twisted 30 turns per inch S, without heat setting and untwisted 30 turns per inch Z and which therefore had substantially no twist or torque therein will have 30 turns of Z-twist imparted thereto and set therein and will then be untwisted a like amount to impart 30 turns of S-twist per inch to this section of yarn. The resulting yarn will have alternate 50 inch sections of 30 turns of Z-twist torque per inch and intervening 50 inch sections of 30 turns of S-twist torque per inch without any lag therebetween.

Obviously, the process may be reversed and the same results obtained. For example, the yarn may first be processed by twisting, setting and untwisting with the setting being continuous but at a low. temperature. Then, the yarn is again twisted, set, and untwisted, the twist being opposite to that initially applied and the setting being intermittent and at a higher temperature than the initial set.

It is thus seen that we have provided an improved dual torque yarn wherein single ends of yarn each has contiguously oppositely twisted or high torque portions therein throughout the length thereof thus obviating the necessity of using more than one yarn in order to knit a fabric having stretchable properties and which will not tend to curl but, instead, will lie flat. It might be stated that the improved yarn of the present invention is a lively yarn having latent torque therein and it is not actually stretchable in itself but articles, such as hosiery, knit therefrom, have a high degree of elasticity. Lively yarns are opposed to stretchable synthetic thermoplastic yarns in that stretchable yarns are generally made from multifilament material which has been twisted and heat set and then untwisted and sometimes plied with another yarn which has been twisted in the opposite direction from the first yarn to form a plurality of permanent spring-like coils or spirals therein, or which have been crimped or otherwise treated so that they are inherently highly elastic prior to being knit into a fabric.

In the specification the preferred embodiments of the invention have been set forth, and although specific terms are used therein, they are used in a generic and descriptive sense only and not for the purposes of limitation, the scope of the invention being defined in the ap pended claims.

We claim:

.1. That method of imparting liveliness to a synthetic yarn which comprises continuously twisting, heat-setting and untwisting said yarn, then continuously twisting said yarn while alternately heat-setting sections of said yarn, then untwisting said yarn with the second twisting being in a direction opposite to the intial twisting and the second setting temperature being higher than the initial setting temperature.

2. A lively synthetic yarn produced by the method of claim 1. v

3. The method of treating synthetic yarn to create a dual torque liveliness therein comprising the steps of twisting the yarn in one direction while constantly heatsetting the moving yarn, untwisting the yarn, twisting the yarn in the opposite direction while intermittently heatsetting the moving yarn at a highereffective temperature than that of the initial heat-setting, again untwisting the Y rn.

4. A synthetic yarn having a dual torque liveliness produced by the method of claim 3.

5. The method of treating synthetic yarn to create dual torque liveliness therein including the steps of moving the yarn past and in constant heat-setting relation to a heat source while twisting the yarn in one direction, untwisting the yarn, twisting the yarn in the opposite direction while moving the yarn past a heat source and while intermittently varying the displacement between the latter heat source and the yarn to heat-set alternately spaced 10 2751747 portions of the moving yarn at a greater effective temperature than that of the initial heat-setting, and untwisting the yarn.

6. A synthetic yarn having dual torque liveliness produced by the method of claim 5.

References Cited in the file of this patent UNITED STATES PATENTS Burleson June 26, 1956 Disclaimer and Dedication 2,909,028.Marm'/n, H. Gamer and Decoy W. TeWeZZ, Burlington, and Ohm-lie A. Miles, Alamance, N.C. DUAL TORQUE YARN AND METH- OD OF MAKING SAME. Patent dated Oct. 20, 1959. Disclaimer and dedication filed July 81, 1975, by the assignee, Patentem, Inc. Hereby disclaims and dedicates to the Public the entire remaining term of said patent.

[Oficz'al Gazette October 21, 1975.] 

1. THAT METHOD OF IMPARTING LIVELINESS TO A SYNTHETIC YARN WHICH COMPRISES CONTINUOUSLY TWISING HEAT-SETTING AND UNTWISTING SAID YARN, THEN CONTINUOUSLY TWISTING SAID YARN WHILE ALTERNATELY HEAT-SETTING SECTIONS OF SAID YARN, THEN UNTWISTING SAID YARN WITH THE SECOND TWISTING BEING IN A DIRECTION OPPOSITE TO THE INTIAL TWISTING AND THE SECOND SETTING TEMPERATURE BEING HIGHER THAN THE INITIAL SETTING TEMPERATURE.
 2. A LIVELY SYNTHETIC YARN PRODUCED BY THE METHOD OF CLAIM
 1. 